Using phase array antennas with the 802.11 MAC protocol

Inexpensive analog phase array antennas are on the verge of becoming widely available. These versatile antennas are capable of very rapidly altering their gain pattern to form complex patterns. However, it is not immediately obvious how to best exploit their capabilities. Previous research has shown that problems arise when using the stock 802.11 MAC protocol with directional antennas, and new MAC protocols have been designed to address these issues as well as exploit some of their new capabilities. Unfortunately moving to a new MAC layer means abandoning a wealth of inexpensive 802.11 wireless equipment since these cards are not very amenable to such extensive modification. In this work, we propose, implement, and evaluate a scheme which uses the flexible gain pattern formation ability of a phase array antenna to exploit the enhanced spatial diversity potential of directional transmission in a community networking environment while still functioning with the existing 802.11 MAC.